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Mini Split AC

Exploring The Magic Of Ductless Mini Split Air Conditioners

You may have come across terms like ductless, mini split AC, or mounted cooling systems, but do you know what a ductless air conditioner system is all about? Well, it’s exactly what the name suggests – no ductwork required!

I remember my first encounter with a ductless air conditioner; I couldn’t believe it was cooling the room without any ducts! Despite their popularity, many homeowners are still unfamiliar with how mini split AC works and whether they are suitable for upgrades or new construction projects. 

If you wonder, “How does ductless air conditioning work?” you’re in luck! This article will give you everything you need about ductless air conditioners. 

But before we dive into the details of how a mini split AC works, let’s first understand the functioning of a typical air conditioner.

How Does A Standard Air Conditioner Work?

How does an AC work

A standard air conditioner, often referred to as a “central air conditioner” or “split system air conditioner,” generally consists of:

  • A thermostat that regulates system operation.
  • An outdoor unit housing a fan, condenser coil, and compressor.
  • An indoor unit (usually a fan coil) containing the evaporator coil and fan to circulate cooled air.
  • Copper tubing allows the refrigerant to flow between the indoor and outdoor units.
  • An expansion valve regulating the amount of refrigerant entering the evaporator coil.
  • Ductwork enabling air circulation from the indoor unit to various living spaces and back.

Operating much like a refrigerator, air conditioners transfer heat from the interior of a home to the warmer outside environment.

The cooling process involves two simultaneous processes – one inside the house and one outside:

  • Inside the house (the “cold side” of the system), warm room air passes through cold coils filled with refrigerant. The refrigerant absorbs heat from the room air as it changes from liquid to gas. Cooled air is then returned to the house.
  • Outside the house (the “hot side” of the system), the refrigerant gas is compressed before entering the large coils of the outdoor unit. Heat is released outdoors as the refrigerant re-liquefies, and a large fan draws outside air through the outer coils to dissipate the absorbed heat from the house.

This creates a continuous cycle of removing heat and moisture from indoor air, returning cold air to the home, and releasing heat and moisture.

Now that we’ve covered how air conditioners work, let’s explore the intricacies of ductless mini split air conditioners.

Understanding Ductless Mini Split AC

mini split ac

In its simplest form, a ductless mini split AC system comprises one outdoor unit and one indoor unit connected by refrigerant tubing and electrical wiring. With no need for ductwork, the indoor unit, often wall-mounted, delivers cooled air directly to the living area. This setup is a single-zone system that provides cooling comfort to a specific area.

Ductless HVAC systems are incredibly versatile and straightforward to install due to the variety of interior unit types available, requiring only a small hole in the wall for wiring and refrigerant line connections.

How Do Ductless Air Conditioning Systems Work?

So, how exactly do ductless mini split AC work?

The cooling process of ductless air conditioning systems is similar to that of standard central air conditioners. However, unlike central air conditioning, a ductless indoor unit directly blows chilled air into a single living space, which uses a centrally positioned indoor unit and a system of ducts and vents to cool the entire home.

A complete ductless mini split air conditioner system must include at least one outdoor unit housing a compressor, condenser coil, and fan and one indoor unit with an evaporator coil and blower fan. Copper refrigerant tubing and electrical wiring connect the two units.

All ductless mini split AC operate according to these steps:

  • The outdoor compressor unit pumps chemical refrigerant through the refrigerant tubing to the indoor unit’s coil.
  • Heat and humidity are removed from indoor air blowing across the coil as the liquid refrigerant turns to gas.
  • Cooler and less humid air is then circulated back into the living space.
  • The liquid refrigerant absorbs the warmth removed from the indoor air.
  • The refrigerant, now in gas form, cycles back to the outdoor coil, which is converted to a liquid, releasing heat energy through the outdoor coil.

Pros & Cons Of Ductless Mini Split AC

Ductless air conditioning systems are gaining popularity in single-family homes. While the units may be slightly more expensive than traditional ducted AC components, the absence of ductwork installation and improved energy efficiency offset this cost. 

Now that we’ve explored how ductless mini splits work let’s consider some of their advantages and disadvantages:


  • Easy installation without ductwork: With no need for ducting, installation is hassle-free, requiring only a small hole in the wall for piping connection between the indoor and outdoor units. Moreover, the outdoor compressor unit powers the indoor unit, eliminating the need for additional indoor wiring.
  • Highly energy-efficient cooling system: Ductless systems don’t suffer from duct leakage, making them approximately 20 to 30 percent more efficient than ducted systems.
  • Precise cooling with inverter compressor technology: Inverter-controlled compressors ensure precise cooling temperatures, maintaining indoor temperatures with minimal fluctuations compared to typical single-stage systems.
  • Quiet operation: Ductless outdoor systems with inverter-controlled variable-speed compressors offer longer, quieter comfort cycles, and their outdoor unit can be installed further away from living spaces for a quieter operation.
  • Allergy control: Ductless systems improve indoor air quality by using filters in each indoor unit, ensuring air quality control and no air cross-contamination between rooms.


  • Higher initial installation cost compared to conventional ducted systems (though long-term utility savings may offset this cost).
  • Wall-mounted and visible: mini split AC units are visible inside a room, unlike conventional HVAC systems. However, most designs are elegant and pleasing to the eye.

Determining the Number Of Ductless AC Units Needed

ac repair

You’ll need multiple units to cool your entire home with a mini split AC system. The number of units required depends on the rooms you want to cool. In general, one mini split AC unit can effectively cool the room in which it is placed, and cooling the main rooms will impact the entire house’s comfort. 

Consider the rooms that need cooling to keep the whole house comfortable and decide which rooms you want to cool individually.

For cooling the entire home, focus on covering large spaces, especially the ground floor and master bedrooms. Usually, you can use four indoor units with one outdoor unit. 

However, it’s always best to consult a professional before deciding on your home system.

Available Sizes Of Ductless Air Conditioning Systems

Let’s discuss some parameters used to determine the size of the mini split AC you may need for your home.

The power required for a mini split AC unit depends on the room size. A quick rule of thumb for estimating your cooling needs is:

Area of Room in Square Feet (Length x Width) x 25 = BTU Required

For instance, a room measuring 18′ x 14′ is approximately 252 square feet. The estimated BTU requirement would be 252 x 25 = 6,300 BTU per hour of cooling.

Please note that the above values are approximate and based on standard room dimensions. Many other factors, such as ceiling height, insulation quality, home age, outdoor climate, number and quality of windows, and sun exposure, can affect the load calculation. 

It’s essential to have your local HVAC expert perform a proper calculation considering all relevant factors.

Ductless Mini Split AC Maintenance

Having established that ductless mini split air conditioners are one of the most efficient and cost-effective cooling options, ensuring that yours is well-maintained is crucial. Neglecting proper maintenance can shorten its lifespan and reduce its efficiency. Here are some maintenance tips to keep your system functioning at its best:

  • Ensure the unit is securely mounted on its base, and the fan wheel and blower assembly are balanced. Clean excess debris from the outside of the unit and spray the coils clean from the inside out.
  • Inspect and clean the outdoor condensing unit as you would for a central air conditioning system.
  • To prevent dangerous biological growth, apply a fungistat and bacteriostat to clean coils.
  • Turn off and disconnect the power before cleaning, and remember to clean or replace filters regularly.
  • For the best results, seek the assistance of an HVAC professional to ensure your ductless cooling system is operating optimally.


ac repair, hvac company

You can confidently choose the right cooling system for your home with a solid understanding of how ductless mini split AC work. 

At Air Comfort Systems, our HVAC experts are ready to install efficient and reliable ductless mini split heating and cooling systems or air conditioners, providing you with year-round personal comfort. Contact or visit us today.

Enjoy the benefits of ductless cooling and make your home a haven of comfort with our expert services.